Cell division during Xenopus gastrulation influences neuroectoderm patterning

Oriented cell division is emerging as a fundamental morphogenetic mechanism driving tissue elongation and axis formation. Although Xenopus laevis embryos can undergo gastrulation and neurulation in the absence of cell division, the specific contribution of mitosis during gastrulation remains poorly defined. Here, we systematically examine the role of cell division during gastrulation in neural plate formation and anterior-posterior (A-P) patterning. Using Hydroxyurea and Aphidicolin (HUA) to block cell division, combined with in situ hybridization and time-lapse imaging, we analyzed division dynamics and developmental outcomes in the dorsal mesoderm and neuroectoderm. Consistent with previous work, we find that cell division is dispensable for dorsal mesoderm patterning and neural tube closure. Strikingly, however, inhibition of cell division during gastrulation profoundly disrupts neural plate patterning, leading to severe head and trunk defects that manifest at tailbud stages. This phenotype is accompanied by markedly reduced expression of key anterior neural markers (bf1 and krox20), indicating a failure to properly specify the forebrain, midbrain, and hindbrain domains. These defects reveal an essential role for cell division in early neural regionalization rather than in tissue formation per se. Moreover, quantitative analysis shows that cell divisions are abundant throughout the gastrulating ectoderm and exhibit strong A-P orientation, particularly in the dorsal posterior region. Together, our results identify A-P oriented cell division as a conserved and previously underappreciated mechanism required for neural plate elongation and anterior neural patterning during vertebrate development.